At the recently unveiled Park Hyatt New York, the 25th-floor pool has a wall of windows that look out over Carnegie Hall--and underwater speakers that pipe in music curated by the neighboring venue. Rooms, from $795; 153 W. 57th St.; 646-774-1234; parkhyatt.com.
The centerpiece of the underground pool at the new Peninsula Paris takes the form of a shimmering floor-to-ceiling waterfall in the middle of an otherwise understated ambiance. Rooms, from $1,360; 19 Av. Kléber; 33-19/58-12-28-88; peninsula.com.
The Mandarin Oriental Hyde Park London has a chic, new subterranean stainless-steel lap-swimming oasis that is 56 feet long with two lanes. Rooms, from $755; 66 Knightsbridge; 44-20/7235-2000; mandarinoriental.com.